According to a Bay Area television station’ s investigative exposé, California hospitals reported 6,282 adverse events to the state over the last 4 fiscal years combined. It sounds like a lot until you realize that there are 410 hospitals in California. That means the average number of adverse events per hospital is only 15.3—fewer than 4 per year.

A brief summary of this story appeared on a website called California Healthline. Its lede mentioned the total number and followed it with possibly the understatement of the year “but the number of actual adverse events could be higher.” Ya think?

Analyzing data by calculating averages sometimes can be misleading. For example, Stanford Hospital reported a total of 211 adverse events, and the UCSF Medical Center reported 169. That means some hospitals must have reported far fewer than the average number.

The NBC article has a handy interactive tool that enables the user to click on the name of any hospital in northern California to see its total number and types of reported adverse events. Use it and note that several hospitals reported only one adverse event over the entire 4-year period.

Another interesting statistic is that 3,959 or 63% of the adverse events reported were bedsores. Although bedsores can be serious problems and in most cases preventable, they pale in comparison to death or serious disability associated with the use of restraints or bed rails, operating on the wrong body part, or leaving a foreign body in a patient after surgery.

Surgery performed on the wrong body part occurred 140 times. Even one is too many. One California hospital managed to perform the wrong surgical procedure 10 times during the four years or 7% of all such mistakes. Much as I hate to admit it, that institution may indeed have a system problem.

Another hospital reported 32 instances of death or disability related to restraints or bed rails. Eight such events per year seems like a lot to me.

Do you think that Stanford Hospital or UCSF Medical Center are less safe than hospitals that reported only one adverse event? I don’t. The chief medical officer of UCSF was interviewed and pointed out that his institution is diligent about identifying and tracking adverse events. I would take my chances at his hospital over a hospital that reports one adverse event every 4 years.

Statewide, death during or up to 24 hours after surgery occurred 108 times. This does not mean that all were caused by a mistake. Without reviewing each record, it is impossible to know how many of these deaths were preventable.

As I have written before, every complication or adverse event is not necessarily the result of a mistake, nor are they all preventable.

In a letter to California officials referencing the NBC story, an organization called Consumer Watchdog called for audits of all hospitals to identify unreported adverse events and fines for those not in compliance with state law.

Is the state equipped to audit all 410 hospitals? Probably not. I suggested starting with those that reported one adverse event in 4 years.

Skeptical Scalpel is a retired surgeon and was a surgical department chairman and residency program director for many years. He is board-certified in general surgery and critical care and has re-certified in both several times. He blogs at and tweets as @SkepticScalpel. His blog averages over 1400 page views per day, and he has over 10,800 followers on Twitter.